The answer: x = 200 .
________________________________________________Explanation:________________________________________________Given the equation:
________________________________________________(1/5)x - (2/3)y = 30 ;
What is the value of "x" when "y" = 15 ?
_____________________________________Plug in "15" for "y" into the equation; and solve:
(1/5)x - (2/3)*15 = 30 ;
Note:

OR:
![\frac{2}{3} * \frac{15}{1} = ? ;\\The "3" cancels out to a "1" ; and the "15" cancels out and is replaced with a "5" ; since; "(15÷3=5") ; and since: "(3÷3=1)" ; and we have:\\[tex] \frac{2}{1} * \frac{5}{1} = \frac{2*5}{1*1} = \frac{10}{1} = 10 ; ](https://tex.z-dn.net/?f=%20%5Cfrac%7B2%7D%7B3%7D%20%2A%20%5Cfrac%7B15%7D%7B1%7D%20%3D%20%20%3F%20%20%3B%5C%5CThe%20%223%22%20cancels%20out%20to%20a%20%221%22%20%3B%20and%20the%20%2215%22%20cancels%20out%20and%20is%20replaced%20with%20a%20%225%22%20%3B%20since%3B%20%22%2815%C3%B73%3D5%22%29%20%3B%20and%20since%3A%20%20%22%283%C3%B73%3D1%29%22%20%3B%20%20%20and%20we%20have%3A%5C%5C%5Btex%5D%20%5Cfrac%7B2%7D%7B1%7D%20%2A%20%20%5Cfrac%7B5%7D%7B1%7D%20%3D%20%20%5Cfrac%7B2%2A5%7D%7B1%2A1%7D%20%3D%20%20%5Cfrac%7B10%7D%7B1%7D%20%3D%2010%20%20%3B%0A%0A%20%20%20)
Or: [tex] \frac{2}{1} * \frac{5}{1} = 2 * 5 ; (since 2/1 = 2; and since 5/1 = 6 ;
→ 2 * 5 = 10 ;
______________________________________________________So, we can rewrite the equation:
_____________________________________________________(1/5)x - (2/3)y = 30 ; and replace "(2/3)y" with "10") ;
(1/5)x - 10 = 30 ;
Add "10" to EACH SIDE of the equation;
(1/5)x - 10 + 10 = 30 + 10 ;
to get: (1/5)x = 40 ;
Now, multiply EACH SIDE of the equation by "5" ; to isolate "x" on one side of the equation ; and to solve for "x" ;
________________________________________________ 5* (1/5)x = 40 * 5 ;
x = 200 ;
______________________________________The answer: x = 200 .______________________________________